The correct option is (a).
Explanation
Insects, such as cockroaches, possess a specialized respiratory system distinct from vertebrates. Instead of lungs or gills, they utilize a network of tubes known as the tracheal system to transport oxygen directly to the tissues.
Statement-wise Analysis:
- Statement 1 is Correct: Insects have small openings on the lateral sides of their body known as spiracles. Air enters the body through these spiracles, which are regulated by muscular valves to prevent water loss.
- Statement 2 is Incorrect: Insects do not possess lungs. Instead, they rely on a network of air tubes called tracheae that subdivide into smaller tracheoles. These tubes carry oxygen from the air directly to the cells and transport carbon dioxide away. Lungs are characteristic of vertebrates like mammals, reptiles, and birds.
- Statement 3 is Incorrect: The tracheal system is specific to insects. Earthworms do not have a tracheal system; they respire through their moist skin (cutaneous respiration). Gases are exchanged by diffusion across the body surface, which must remain moist for the process to occur.
Key Takeaway:
Insects respire through a tracheal system connected to the exterior via spiracles, whereas earthworms rely on cutaneous respiration through moist skin. Neither group utilizes lungs.